One thing I can say, I grew up in a Roman Catholic household (not polish, but Italian/Irish) and I was the only daughter. In fact, I was the only child. I actually did live at home until I was 28 years old. I went away to college but got a job near home and just decided to live there out of convienence. It was only supposed to be for a little while, but everytime I got a house w/ roommates or an apartment lined up, my mom pulled a guilt trip or told me I wasn't responsible enough to live by myself. So I stayed. I can understand the Catholic "guilt" she may be going through. My mom expected me to live at home until my wedding day. And, I didn't really fight her....until I met a guy on the internet.
He lived in Guam. We talked for 6 months, then he flew to the states to meet me. My parents did let him stay in our house but he slept on the couch. 2 weeks after he left, I told mom I was moving to Guam...2 weeks later. I already had my ticket ordered (paid by him). I went to Guam with 3 suitcases and $40 in my pocket. That was the ONLY way I could get out from under her thumb. And, it was the hardest thing I ever did, but it was the best thing for me. The relationship lasted 4 years before it fizzled out, but I grew up so much in that time.
Your girlfriend needs to stand up for herself. And, if she cares about you, she has to make an effort too. My mom basically didn't speak to me for the last 2 weeks I was home. If she did, it was a sarcastic comment that I ignored, or she would just start bawling and asking "where did I go wrong..."
I hated to do it to her, but I had to do something for myself. And, she realized after a few months that I NEEDED to do this, she was ok and both my parents were so proud of me for taking that step. It sounds like your girlfriend is at the same place. She NEEDS to do something to start HER life and not live for her parents.
I just wanted to say I may understand why she is still living with her parents. Old school Catholics are tough.